Protective structure suitable for replacing moderator at treatment room end

Abstract

The utility model discloses a protective structure suitable for replacing a moderator at a treatment room end, and aims to solve the problems that in the moderator replacing process, a used target needs to be transferred to a waste target containing position and then replaced with a new target material, vacuum recovery after vacuum breaking needs a long time, and the replacement cost is low. And if the target is decommissioned before reaching the decommissioning state, the target is wasted, and the accommodating cost is increased. The device comprises a reflector, a slowing-down body and a target material are arranged in the reflector, a movable door curtain is installed in the reflector, and the door curtain moves to block the target material and the slowing-down body in the neutron transmission direction. According to the protective structure suitable for replacing the moderator at the treatment room end, the neutron source can be isolated when the moderator is replaced at the treatment room end, and damage to a human body caused by radiation leakage of the neutron source target is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of boron neutron capture therapy, and more particularly to a protective structure suitable for replacing a moderator at the end of a treatment room. Background Art

[0002] Currently, during boron neutron capture therapy, adjustments to the beam shaping structure are often required to adjust the neutron performance at the exit to accommodate treatment depths of tumors. Alternatively, adjustments to the moderator structure can be made to convert the epithermal neutron beam into a thermal neutron beam, enabling superficial skin cancer treatment. Adjusting the exit neutron performance requires adjustments to the beam shaping structure and the moderator core, necessitating system downtime for maintenance. During this time, the neutron source targets, having been irradiated and carrying a certain amount of radioactivity, expose workers to radiation exposure during replacement, necessitating appropriate personnel protection. However, if the used targets are transferred to a waste target storage area and then replaced with new ones, the recovery time after breaking vacuum is significant, compromising patient treatment efficiency. Furthermore, decommissioning targets before they reach retirement status leads to target waste and increased storage costs. Utility Model Content

[0003] In order to overcome the above-mentioned shortcomings, the present invention provides a protective structure suitable for replacing the moderator at the treatment room end, which can isolate the neutron source when replacing the moderator at the treatment room end, thereby preventing radiation leakage from the neutron source target from causing damage to the human body.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions: a protective structure suitable for replacing a moderator at the end of a treatment room, comprising a reflector, a moderator and a target material arranged inside the reflector, and a movable door curtain installed inside the reflector, the movement of which can block the target material and the moderator in the direction of neutron transmission.

[0005] When the moderator needs to be replaced, the equipment is shut down and the target retracts behind a curtain. The curtain's movement separates the target and moderator in the direction of neutron transmission, isolating the neutron source. The moderator is then replaced from the treatment room end (neutron exit). Since the gamma rays emitted by the target are isolated by the reflector and curtain, the moderator can be replaced without exposing the target to radiation. Once the moderator is replaced, the curtain returns to its original position, freeing the target and moderator from obstruction, creating a complete proton channel. The target then advances to its normal operating position. Finally, the equipment is restarted and beam delivery resumes.

[0006] Because of the movable door curtain, during normal operation, the door curtain does not block the target material and the moderator, forming a complete proton channel. When the moderator is replaced, the door curtain moves, blocking the target material and the moderator, thus avoiding radiation leakage from the neutron source target that may occur when the moderator is replaced from the treatment room side.

[0007] The protective structure of the present patent application, which is suitable for replacing the moderator at the treatment room end, can isolate the neutron source when replacing the moderator at the treatment room end, thereby preventing radiation leakage from the neutron source target from causing damage to the human body.

[0008] Preferably, a through hole is provided on the door curtain, and the movement of the door curtain causes the through hole to be aligned with or separated from the target material. When the through hole on the door curtain is separated from the target material, the door curtain isolates the target material.

[0009] The curtain moves, causing the holes in the curtain to shift and separate from the target. This now isolates the target and the neutron source, allowing the moderator to be replaced at the treatment room end (neutron exit). Once the moderator is replaced, the curtain returns to its original position, aligning the holes in the curtain with the target to form a complete proton channel, and the target moves forward to its normal operating position.

[0010] Preferably, a mounting hole and a mounting cavity that are interconnected are provided in the reflector, the mounting hole penetrates the proton beam pipe with the target material, and the moderator is installed in the mounting cavity.

[0011] The mounting hole provides space for the proton beam pipe and target, while the mounting cavity provides space for the moderator. The target is connected to the proton beam pipe and moves with it.

[0012] Preferably, the reflector includes a back reflector and a side reflector; the back reflector and the side reflector are an integrated structure; or the back reflector and the side reflector are two independent units connected to each other.

[0013] The back reflector plays a reflective isolation role on the proton beam pipeline. The side reflectors surround the moderator and play a reflective isolation role.

[0014] In the first solution, the door curtain is installed in the back reflector.

[0015] The door curtain is installed in the back reflector, and the door curtain itself can shield gamma rays and reflect neutrons.

[0016] In the second solution, the door curtain is installed in the side reflector.

[0017] The door curtain is installed in the side reflector, and the door curtain itself can shield gamma rays and reflect neutrons.

[0018] Preferably, avoidance grooves are provided in the reflector and the door curtain respectively, and the door curtain is adapted to be plugged into the avoidance grooves.

[0019] The setting of the avoidance groove provides a space for the door curtain to prevent interference and jamming during the movement of the door curtain.

[0020] Preferably, the door curtain is provided with a corresponding connecting piece, a slide rail is provided on the connecting piece, and the door curtain is slidably connected to the slide rail.

[0021] The setting of the connecting piece facilitates the installation of the door curtain. The door curtain is slidably connected to the slide rail, making the movement of the door curtain smooth and reliable.

[0022] Preferably, the door curtain is connected to a screw sleeve, which is adapted to be connected to a screw driven by a motor, and the rotation of the screw drives the door curtain to move.

[0023] The motor drives the screw to rotate, and through the cooperation between the screw and the screw sleeve, the door curtain is driven to move.

[0024] In another solution, the door curtain is connected to the telescopic rod of the piston cylinder, and the operation of the piston cylinder drives the door curtain to move.

[0025] The movement of the door curtain is driven by a piston rod, and the structure is simple and the operation is reliable.

[0026] Preferably, the door curtain is arranged to rotate, and the deflection movement of the door curtain blocks the target material and the moderator in the direction of neutron transmission.

[0027] The door curtain adopts a swinging motion. By controlling the swing angle, the alignment or misalignment separation of the through hole and the target material can be precisely controlled.

[0028] Preferably, a telescopic section is provided on the proton beam pipe, and the axial telescopic extension of the proton beam pipe drives the target material to move forward and backward relative to the reflector.

[0029] The setting of the telescopic section facilitates the telescopic movement of the proton beam pipeline.

[0030] Preferably, the reflector is connected to a moving assembly, and the moving assembly drives the reflector to move back and forth relative to the proton beam pipe.

[0031] The reflector is driven to move by the moving assembly, thereby achieving relative movement of the reflector and the proton beam pipe.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) the protective structure of the present patent application, which is suitable for replacing the moderator at the end of the treatment room, can isolate the neutron source when replacing the moderator at the end of the treatment room, thereby preventing the radiation leakage of the neutron source target from causing damage to the human body; (2) the target material does not need to be disassembled when the moderator is replaced, thereby avoiding the operation of transferring the used target to the waste target storage area and then replacing it with a new target material, saving the time of breaking the vacuum and restoring the vacuum, and being conducive to improving the treatment efficiency; and decommissioning the target before it reaches the decommissioned state will bring about problems such as target waste and increased storage costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural diagram of embodiment 1 of the present utility model.

[0034] Figure 2 It is a schematic diagram of the installation of the door curtain of Example 1 of the present utility model.

[0035] Figure 3 It is a cross-sectional view of Example 1 of the present utility model.

[0036] Figure 4 It is a cross-sectional view of Example 2 of the present utility model.

[0037] Figure 5 It is a door curtain connection diagram of embodiments 3 and 6 of the present utility model.

[0038] Figure 6 It is a structural diagram of embodiment 4 of the present utility model.

[0039] Figure 7 It is a schematic diagram of door curtain installation in embodiment 4 of the present utility model.

[0040] Figure 8 It is a cross-sectional view of embodiment 4 of the present invention.

[0041] Figure 9 It is a cross-sectional view of Example 5 of the present utility model.

[0042] Figure 10 It is a side view of embodiment 7 of the present utility model.

[0043] In the figure: 1. base, 2. proton beam pipe, 3. target, 4. door curtain, 5. through hole, 6. back reflector, 7. side reflector, 8. mounting cavity, 9. moderator, 10. mounting hole, 11. avoidance groove, 12. slide rail, 13. telescopic section, 14. screw, 15. slide seat, 16. piston cylinder, 17. vertical rod, 18. cross bar, 19. slider, 20. upper cross beam, 21. lower cross beam. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0045] Example 1: A protective structure suitable for replacing a moderator at the end of a treatment room (see attached Figure 1 To the attached Figure 3 ), including a base 1 and a reflector, the reflector is fixedly mounted on the base 1,

[0046] A moderator 9 and a target 3 are disposed within the reflector. A movable curtain 4 is mounted within the reflector. Movement of the curtain 4 can block the target 3 from the moderator 9 in the direction of neutron transmission. A through-hole 5 is provided in the curtain 4. Movement of the curtain 4 allows the through-hole 5 to align with or separate from the target 3. When the through-hole 5 is displaced from the target 3, the curtain 4 isolates the target 3. A connecting mounting hole 10 and mounting cavity 8 are provided within the reflector. The mounting hole 10 extends into the proton beam conduit 2 carrying the target 3. The moderator 9 is mounted within the mounting cavity 8.

[0047] The reflector has horizontal mounting holes for the proton beam pipe with the target material to pass through. The target end of the proton beam pipe extends into the reflector through the mounting holes. Protons passing through the proton beam pipe strike the target material, producing neutrons. The neutrons are then moderated by the moderator to produce a neutron beam that meets the treatment requirements.

[0048] The reflector includes a back reflector 6 and a side reflector 7. The back reflector 6 and the side reflector 7 are integrally formed; alternatively, the back reflector 6 and the side reflector 7 are connected to each other as two independent units. A mounting hole 10 is provided in the back reflector 6, and a mounting cavity 8 is provided in the side reflector 7. The proton beam conduit 2 is connected to the back reflector 6 and is movable. A moderator 9 is installed in the side reflector 7.

[0049] The proton beam conduit 2 is provided with a telescopic section 13. Axial telescoping of the proton beam conduit 2 drives the target 3 forward and backward relative to the reflector, positioning the door curtain 4 in front of the target 3. The telescopic section 13 is typically a bellows. The proton beam conduit is driven axially by an axial drive mechanism (not shown). The axial drive mechanism comprises a motor and a screw, which is rotatably connected to a slide. A connecting portion is provided on the outer wall of the proton beam conduit, with the screw threadedly connected to the connecting portion. The connecting portion is then slidably connected to the slide. The motor output shaft is connected to the screw, and the rotation of the motor drives the axial movement of the proton beam conduit.

[0050] The door curtain 4 is installed in the side reflector 7. Avoidance grooves 11 are correspondingly provided in the reflector and for the door curtain 4, and the door curtain 4 is adapted to be inserted into the avoidance grooves 11. A corresponding connector is provided for the door curtain 4, which is installed on the base 1. A slide rail 12 is provided on the connector, and the door curtain 4 is slidably connected to the slide rail 12. The avoidance groove 11 is provided in the side reflector 7. The door curtain 4 is connected to a screw sleeve, which is adapted to be connected to a screw rod 14 driven by a motor. The rotation of the screw rod 14 drives the door curtain 4 to move. The connector includes two vertical rods 17, each of which is provided with a slide rail 12. The slide rail 12 is vertically arranged. A cross bar 18 is provided on the upper part of the door curtain 4. Slide blocks 19 are provided at both ends of the cross bar 18. The slide blocks 19 are adapted to be connected to the slide rail 12. The through hole 5 on the door curtain 4 is placed in the mounting cavity 8 of the mounting cavity 8 of the side reflector 7. The door curtain 4 moves upward to cause the through hole 5 to be dislocated and separated from the mounting cavity 8 of the side reflector 7. An upper crossbeam 20 and a lower crossbeam 21 are connected between the two vertical poles 17. A motor for driving the door curtain 4 to move is installed on the upper crossbeam 20. A screw 14 is installed between the upper crossbeam 20 and the lower crossbeam 21. The motor output shaft is connected to the screw 14. A slide 15 is provided on the door curtain 4. The screw sleeve is installed on the slide 15. The motor drives the screw 14 to rotate, thereby driving the door curtain 4 to move up and down.

[0051] The back reflector 6 and the side reflector 7 are both designed to reflect neutrons in the non-exit direction back to the moderator 9 as much as possible. Therefore, materials with high reflection cross-sections and low absorption cross-sections are required. Lead is the most commonly used reflector material in beam shaping systems. It has high elastic scattering and inelastic scattering cross-sections and is suitable as a reflector material for epithermal neutron beams.

[0052] The material of the curtain 4 is primarily heavy nuclear material or related gamma-shielding materials capable of shielding gamma rays emitted after activation of the neutron source target. In principle, the curtain 4, back reflector 6, and side reflectors 7 are generally made of the same material to avoid local material inconsistencies that could affect neutron performance at the end of the beam shaping device. For example, lead is used as the material for the curtain 4 and reflectors. However, this can be adjusted based on demand. Some reflector materials, such as graphite, have weak gamma-ray shielding capabilities, necessitating a change in the curtain 4 material. However, if a certain degree of reflective performance is still required, lead remains a good choice.

[0053] When the moderator 9 needs to be replaced, the equipment is shut down, the proton beam duct 2 is retracted, the end of the proton beam duct 2 is moved away from the moderator 9, and the curtain 4 is positioned between the target 3 and the moderator 9. The curtain 4 moves, causing the through-holes 5 on the curtain 4 to be offset and separated from the target 3. The curtain 4 now isolates the target 3 and the neutron source. Moderator 9 is then replaced from the treatment room end (the neutron exit end). Since the gamma rays emitted by the target are now isolated by the reflector and the curtain 4, the operator can replace the moderator 9 without exposing the target to radiation. When the moderator 9 is replaced, the curtain 4 returns to its original position, aligning the through-holes 5 on the curtain 4 with the target 3 to form a complete proton passage. The proton beam duct 2 then advances and returns to its normal operating position. Finally, the equipment is restarted to resume beam delivery.

[0054] Because of the movable door curtain 4, during normal operation, the through-holes 5 on the door curtain 4 align with the target 3 to form a complete proton passage. When the moderator 9 is replaced, the door curtain 4 moves, causing the through-holes 5 on the door curtain 4 to shift and separate from the target 3. The door curtain 4 isolates the target 3, thus preventing radiation leakage from the neutron source target that may occur when the moderator 9 is replaced from the treatment room side.

[0055] Without the technical solution of this patent and other measures, the scheme for replacing the moderator 9 while ensuring the safety of the workers becomes the following process:

[0056] (1) When the moderator 9 needs to be replaced, the equipment is shut down and the target material 3 is broken into vacuum. Then, the neutron source target is removed from the end of the accelerator through the target replacement system or by workers and transferred to the waste target storage box.

[0057] (2) The moderator 9 is replaced from the end of the treatment room (neutron outlet). Since the target has been transferred, there is no need to worry about irradiation of on-site workers when the moderator 9 is replaced.

[0058] (3) After the moderator 9 is replaced, a new target is placed at the end of the accelerator, and then vacuum is evacuated until the vacuum at the target reaches the beam emission standard.

[0059] (4) Turn on the device and continue to emit beams.

[0060] From the above comparison, it can be seen that in order to ensure the safety of on-site workers, the activated radioactive targets need to be transferred to the containment area, which will bring the following problems:

[0061] (1) Since the moderator 9 is not replaced during the target decommissioning stage, and the dismantled targets are basically no longer usable, the targets are stored before the decommissioning deadline. On the one hand, the cost of replacing the moderator 9 is increased, and on the other hand, it also puts pressure on the storage warehouse for the waste targets, which also increases the storage cost and post-processing cost.

[0062] (2) Since the waste target needs to be moved away, the target needs to be vacuum-broken. After the new target is replaced, the vacuum needs to be re-drawn, which greatly prolongs the time required for the entire process of replacing the moderator 9. It takes at least one to two days, which has a great impact on the treatment efficiency of the treatment device.

[0063] Example 2: A protective structure suitable for replacing a moderator at the end of a treatment room (see attached Figure 4 ), its structure is similar to that of Example 1, the main difference being the drive mechanism for the door curtain 4. In this embodiment, the door curtain 4 is connected to a telescopic rod of a piston cylinder 16, which drives the movement of the door curtain 4. The piston cylinder 16 is securely mounted above the fixed plate 13, with the telescopic rod of the piston cylinder 16 arranged vertically. The telescopic movement of the piston cylinder 16 drives the vertical movement of the door curtain 4. The piston cylinder 16 can be an electric cylinder, a pneumatic cylinder, or an oil cylinder. In this embodiment, an electric cylinder is used, which offers a simple structure and convenient control. The remaining structure is the same as in Example 1.

[0064] Example 3: A protective structure suitable for replacing a moderator at the end of a treatment room (see Appendix Figure 5 ), its structure is similar to that of embodiment 1, and the main difference lies in the movement mode of the door curtain 4. In this embodiment, the door curtain 4 is rotated, and the deflection movement of the door curtain 4 realizes the alignment or misalignment separation of the through hole 5 and the target material 3.

[0065] A deflection motor is mounted on the connector, and its output shaft is connected to the upper portion of the door curtain 4. The deflection motor rotates to drive the door curtain 4. The avoidance groove 11 in this embodiment is fan-shaped, with the width of the door curtain 4 gradually increasing from top to bottom. The door curtain 4 employs an oscillating motion. By controlling the oscillation angle, the alignment or misalignment of the through-hole 5 and the target 3 can be precisely controlled. The remaining structure is the same as in Example 1.

[0066] Example 4: A protective structure suitable for replacing a moderator at the end of a treatment room (see attached Figure 6 To the attached Figure 8 ), its structure is similar to that of Example 1, and the main difference lies in the installation position of the door curtain 4. In this embodiment, the door curtain 4 is installed in the back reflector 6. The avoidance groove 11 is arranged in the back reflector 6. The connecting part includes two vertical rods 17, and the two vertical rods 17 are provided with slide rails 12. The slide rails 12 are arranged vertically. A cross bar 18 is provided on the upper part of the door curtain 4, and sliders 19 are provided at both ends of the cross bar 18. The sliders 19 are adapted to be connected with the slide rails 12. The through hole 5 on the door curtain 4 is placed in the mounting hole 10 of the back reflector 6. The door curtain 4 moves upward to cause the through hole 5 to be misaligned and separated from the mounting hole 10 of the back reflector 6. The proton beam pipe 2 can pass through the through hole 5 on the door curtain 4. An upper crossbeam 20 and a lower crossbeam 21 are connected between the two vertical rods 17. A motor for driving the door curtain 4 is mounted on the upper crossbeam 20. A screw 14 is mounted between the upper crossbeam 20 and the lower crossbeam 21. The motor output shaft is connected to the screw 14. A slide 15 is provided on the door curtain 4. A screw sleeve is mounted on the slide 15. The motor drives the screw 14 to rotate, thereby driving the door curtain 4 to move up and down. The rest of the structure is the same as that of Example 1.

[0067] Example 5: A protective structure suitable for replacing the moderator at the end of the treatment room (see Appendix Figure 9 ), its structure is similar to that of Example 1, the main difference being the installation position of the door curtain 4 and the driving method of the door curtain 4. In this embodiment, the door curtain 4 is installed in the back reflector 6. An avoidance groove 11 is provided in the back reflector 6. The connecting part includes two vertical rods 17, and a slide rail 12 is provided on each of the two vertical rods 17. The slide rail 12 is vertically arranged. A cross bar 18 is provided on the upper part of the door curtain 4, and sliders 19 are provided at both ends of the cross bar 18. The sliders 19 are adapted to be connected with the slide rail 12. The through hole 5 on the door curtain 4 is placed in the mounting hole 10 of the back reflector 6. The door curtain 4 moves upward so that the through hole 5 is dislocated and separated from the mounting hole 10 of the back reflector 6. The proton beam pipe 2 can pass through the through hole 5 on the door curtain 4. The door curtain 4 is connected to the telescopic rod of the piston cylinder 16, and the operation of the piston cylinder 16 drives the door curtain 4 to move. An upper cross beam 20 is connected between the upper ends of the two vertical rods 17, and the piston cylinder 16 is installed on the upper cross beam 20. The telescopic rod of the piston cylinder 16 is connected to the cross bar 18. The telescopic rod of piston cylinder 16 is arranged vertically. The telescopic movement of piston cylinder 16 drives the door curtain 4 up and down. Piston cylinder 16 can be any of an electric cylinder, a pneumatic cylinder, or an oil cylinder. In this embodiment, an electric cylinder is used for its simple structure and convenient control. The rest of the structure is the same as in Example 1.

[0068] Example 6: A protective structure suitable for replacing a moderator at the end of a treatment room (see Appendix Figure 5 ), its structure is similar to that of Example 3, the main difference being the installation position of the door curtain 4. In this embodiment, the door curtain 4 is installed in the back reflector 6. A avoidance groove 11 is provided within the back reflector 6. The door curtain 4 is rotatable, and its deflection motion blocks the target material 3 and the moderator 9 in the direction of neutron transmission. The deflection of the door curtain 4 causes the through hole 5 to be misaligned and separated from the mounting hole 10 of the back reflector 6. The proton beam conduit 2 can pass through the through hole 5 in the door curtain 4. The other structures are the same as those of Example 3.

[0069] Example 7: A protective structure suitable for replacing a moderator at the end of a treatment room (see attached Figure 10 ), its structure is similar to that of embodiment 1, embodiment 2, embodiment 4, or embodiment 5, the main difference being that the door curtain 4 is arranged horizontally in this embodiment, and the corresponding slide rail 12 is also arranged horizontally, thereby achieving left and right movement of the door curtain 4. The other structures are the same as those of embodiment 4, embodiment 5, embodiment 7, or embodiment 8.

[0070] Example 8: A protective structure suitable for replacing a moderator at the end of a treatment room. Its structure is similar to any of Examples 1 to 7, with the primary difference being that in this embodiment, the reflector is connected to a movable assembly, which drives the reflector to move back and forth relative to the proton beam conduit 2. The movable assembly is disposed peripherally to the reflector. When the movable assembly drives the reflector to one side relative to the proton beam conduit, the curtain 4 is positioned to one side of the target 3. The technology for providing a movable assembly around the reflector is already disclosed in existing patents and will not be further discussed in this application. The remaining structure is the same as any of Examples 1 to 7.

[0071] Example 9: A protective structure suitable for replacing a moderator at the treatment room end. Its structure is similar to any of Examples 1 to 8, with the primary difference being that this embodiment lacks a through-hole in the door curtain 4. During normal operation, the door curtain 4 is misaligned with the direction of neutron transmission and does not block the target 3 and moderator 9. When the moderator 9 needs to be replaced at the treatment side, the door curtain 4 moves, blocking the target 3 and moderator 9 in the direction of neutron transmission. The remaining structure is the same as any of Examples 1 to 8.

[0072] In addition, in the present application, the door curtain 4 can move in various ways, including up and down movement, left and right movement, and deflection movement, as long as the through hole 5 and the target material 3 can be aligned or separated by displacement.

[0073] The above-described embodiments are only preferred solutions of the present invention and do not limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A protective structure suitable for replacing a moderator at the end of a treatment room, comprising a reflector, a moderator and a target material arranged inside the reflector, characterized in that: The reflector is provided with interconnected mounting holes and mounting cavities, the mounting holes penetrate into the proton beam pipe with the target material, the moderator is installed in the mounting cavity, and a movable door curtain is installed in the reflector, and the movement of the door curtain can block the target material and the moderator in the direction of neutron transmission.

2. The protective structure for replacing a moderator at the end of a treatment room according to claim 1, characterized in that: A through hole is arranged on the door curtain, and the movement of the door curtain makes the through hole aligned with the target material or separated by misalignment. When the through hole on the door curtain is misaligned with the target material, the door curtain isolates the target material.

3. The protective structure for replacing a moderator at the end of a treatment room according to claim 1, characterized in that: The reflector includes a back reflector and a side reflector; the back reflector and the side reflector are an integrated structure; or the back reflector and the side reflector are connected to each other as two independent units.

4. The protective structure for replacing a moderator at the end of a treatment room according to claim 3, characterized in that: The door curtain is installed in the back reflector.

5. The protective structure suitable for replacing a moderator at the end of a treatment room according to claim 3, characterized in that: The door curtain is installed in the side reflector.

6. The protective structure suitable for replacing a moderator at the end of a treatment room according to claim 1, characterized in that: Avoidance grooves are correspondingly arranged in the reflector body and the door curtain, and the door curtain and the avoidance grooves are adapted to be plugged in.

7. A protective structure suitable for replacing a moderator at a treatment room end according to any one of claims 1 to 6, characterized in that: A connecting piece is correspondingly provided on the door curtain, a slide rail is provided on the connecting piece, and the door curtain is slidably connected to the slide rail.

8. The protective structure suitable for replacing a moderator at the end of a treatment room according to claim 7, characterized in that: The door curtain is connected to a screw sleeve, and the screw sleeve is adapted to be connected to a screw driven by a motor, and the rotation of the screw drives the door curtain to move.

9. The protective structure suitable for replacing a moderator at the end of a treatment room according to claim 7, characterized in that: The door curtain is connected to the telescopic rod of the piston cylinder, and the operation of the piston cylinder drives the door curtain to move.

10. A protective structure suitable for replacing a moderator at a treatment room end according to any one of claims 1 to 6, characterized in that: The door curtain is rotated so that the deflection movement of the door curtain blocks the target material and the moderator in the direction of neutron transmission.

11. The protective structure suitable for replacing a moderator at the end of a treatment room according to claim 1, characterized in that: A telescopic section is provided on the proton beam pipeline, and the axial telescopic extension of the proton beam pipeline drives the target material to move forward and backward relative to the reflector.

12. The protective structure suitable for replacing a moderator at the end of a treatment room according to claim 1, characterized in that: The reflector is connected to the moving assembly, and the moving assembly drives the reflector to move back and forth relative to the proton beam pipe.

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